1.代码

Shader "Custom/Flag2"
{
    Properties
    {
        _MainTex("Texture", 2D) = "white" {}
        //频率
        _FrequencyY("frequency Y", float) = 1  
        //飘动幅度
        _StrengthY("amplitude strengthY", float) = 1
        //波长
        _WaveLengthY("wave length Y", float) = 1
    }
        SubShader
        {
            Tags { "RenderType" = "Opaque" }
            LOD 100

            Pass
            {
                CGPROGRAM
                #pragma vertex vert
                #pragma fragment frag

                #include "UnityCG.cginc"

                struct appdata
                {
                    float4 vertex : POSITION;
                    float2 uv : TEXCOORD0;
                };

                struct v2f
                {
                    float2 uv : TEXCOORD0;
                    float4 vertex : SV_POSITION;
                };

                sampler2D _MainTex;

                float _FrequencyY;
                float _StrengthY;

                float _WaveLengthY;

                v2f vert(appdata v)
                {
                    v2f o;
                    o.uv = v.uv;
                    //y方向的扰动
                    float y = sin(_Time.y * _FrequencyY + (v.vertex.x + v.vertex.z * 0.6) * _WaveLengthY) * o.uv.y;
                    float4 offset = float4(0, 0, 0, 0);
                    offset.y = y * _StrengthY;
                    o.vertex = UnityObjectToClipPos(v.vertex + offset);
                    return o;
                }

                fixed4 frag(v2f i) : SV_Target
                {
                    fixed4 col = tex2D(_MainTex,i.uv);
                    return col;
                }
            ENDCG
        }
    }
}

效果: